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How many methods in the Externalizable interface?
How many methods in the Externalizable interface? There are two methods in the Externalizable interface. You have to implement these two methods in order to make your class externalizable. These two methods are readExternal() and writeExternal().
2012-05-29, 2892👍, 0💬

How many methods in the Serializable interface?
How many methods in the Serializable interface? There is no method in the Serializable interface. The Serializable interface acts as a marker, telling the object serialization tools that your class is serializable.
2012-05-28, 2835👍, 0💬

If a class is located in a package, what do you need to change in the OS environment to be able to use it?
If a class is located in a package, what do you need to change in the OS environment to be able to use it? You need to add a directory or a jar file that contains the package directories to the CLASSPATH environment variable. Let's say a class Employee belongs to a package com.xyz.hr; and is located...
2012-05-28, 2684👍, 0💬

How to define an Interface?
How to define an Interface? In Java Interface defines the methods but does not implement them. Interface can include constants. A class that implements the interfaces is bound to implement all the methods defined in Interface. Emaple of Interface: public interface sampleInterface { public void funct...
2012-05-24, 2601👍, 0💬

How to define an Abstract class?
How to define an Abstract class? A class containing abstract method is called Abstract class. An Abstract class can't be instantiated. Example of Abstract class: abstract class testAbstractClass { protected String myString; public String getMyString() { return myString; } public abstract string anyA...
2012-05-24, 2739👍, 0💬

What is similarities/difference between an Abstract class and Interface?
What is similarities/difference between an Abstract class and Interface? Differences are as follows: Interfaces provide a form of multiple inheritance. A class can extend only one other class. Interfaces are limited to public methods and constants with no implementation. Abstract classes can have a ...
2012-05-23, 2804👍, 0💬

Is Iterator a Class or Interface? What is its use?
Is Iterator a Class or Interface? What is its use? Iterator is an interface which is used to step through the elements of a Collection.
2012-05-23, 2728👍, 0💬

What do you understand by Synchronization?
What do you understand by Synchronization? Synchronization is a process of controlling the access of shared resources by the multiple threads in such a manner that only one thread can access one resource at a time. In non synchronized multithreaded application, it is possible for one thread to modif...
2012-05-22, 2668👍, 0💬

Name the containers which uses Border Layout as their default layout?
Name the containers which uses Border Layout as their default layout? Containers which uses Border Layout as their default are: window, Frame and Dialog classes.
2012-05-21, 2662👍, 0💬

What's the difference between an interface and an abstract class?
What's the difference between an interface and an abstract class? An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implemen...
2012-05-21, 2534👍, 0💬

How could Java classes direct program messages to the system console, but error messages, say to a file?
How could Java classes direct program messages to the system console, but error messages, say to a file? The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This ho...
2012-05-18, 2662👍, 0💬

An application needs to load a library before it starts to run, how to code??
An application needs to load a library before it starts to run, how to code?? One option is to use a static block to load a library before anything is called. For example, class Test { static { System.loadLibrary("path-to-li brary-file");} .... } When you call new Test(), the static block will be ca...
2012-05-18, 2837👍, 0💬

What is NullPointerException and how to handle it?
What is NullPointerException and how to handle it? When an object is not initialized, the default value is null. When the following things happen, the NullPointerException is thrown: --Calling the instance method of a null object. --Accessing or modifying the field of a null object. --Taking the len...
2012-05-17, 2759👍, 0💬

What is more advisable to create a thread, by implementing a Runnable interface or by extending Thread class?
What is more advisable to create a thread, by implementing a Runnable interface or by extending Thread class? Strategically speaking, threads created by implementing Runnable interface are more advisable. If you create a thread by extending a thread class, you cannot extend any other class. If you c...
2012-05-17, 2888👍, 0💬

Jack developed a program by using a Map container to hold key/value pairs. He wanted to make a change to the map. He decided to
Jack developed a program by using a Map container to hold key/value pairs. He wanted to make a change to the map. He decided to make a clone of the map in order to save the original data on side. What do you think of it? ? If Jack made a clone of the map, any changes to the clone or the original map...
2012-05-16, 2872👍, 0💬

Can you have virtual functions in Java?
Can you have virtual functions in Java? Yes, all functions in Java are virtual by default. This is actually a pseudo trick question because the word "virtual" is not part of the naming convention in Java (as it is in C++, C-sharp and VB.NET), so this would be a foreign concept for someone who has on...
2012-05-16, 2867👍, 0💬

What does a well-written OO program look like?
What does a well-written OO program look like? A well-written OO program exhibits recurring structures that promote abstraction, flexibility, modularity and elegance.
2012-05-15, 2973👍, 0💬

What' is Java?
What's Java? Java is an object-oriented programming language developed initially by James Gosling and colleagues at Sun Microsystems. The language, initially called Oak (named after the oak trees outside Gosling's office), was intended to replace C++, although the feature set better resembles that o...
2012-05-15, 3350👍, 0💬

Should BasketOfApples derive from BasketOfFruit? Why or why not?
Given the following classes class Fruit { // … } class Apple : public Fruit { // … } class Peach : public Fruit { // … } // Container of fruit class BasketOfFruit { BasketOfFruit() ; void insert( Fruit & f ) ; // … } // Container of apples class BasketOfApples /* ??? */ { // … } Should BasketO...
2012-05-14, 3946👍, 0💬

In the H file you see the following declaration
In the H file you see the following declaration: class Foo { void Bar( void ) const ; }; Tell me all you know about the Bar() function.
2012-05-14, 4127👍, 0💬

What does the following code do and why would anyone write something like that?
What does the following code do and why would anyone write something like that? void send (int *to, int * from, int count) { int n = (count + 7) / 8; switch ( count % 8) { case 0: do { *to++ = *from++; case 7: *to++ = *from++; case 6: *to++ = *from++; case 5: *to++ = *from++; case 4: *to++ = *from++...
2012-05-11, 4344👍, 0💬

What’s potentially wrong with the following code?
What’s potentially wrong with the following code? long value; //some stuff value &= 0xFFFF; Note: Hint to the candidate about the base platform they’re developing for. If the person still doesn’t find anything wrong with the code, they are not experienced with C++.
2012-05-11, 4032👍, 0💬

Explain virtual inheritance.
Explain virtual inheritance. Draw the diagram explaining the initialization of the base class when virtual inheritance is used. Note: Typical mistake for applicant is to draw an inheritance diagram, where a single base class is inherited with virtual methods. Explain to the candidate that this is no...
2012-05-10, 4456👍, 0💬

Anything wrong with this code?
Anything wrong with this code? T *p = 0; delete p; Note: Typical wrong answer: Yes, the program will crash in an attempt to delete a null pointer. The candidate does not understand pointers. A very smart candidate will ask whether delete is overloaded for the class T.
2012-05-10, 3825👍, 0💬

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